A Novel Catalytic Process for Generating Hydrogen Gas from Aqueous Borohydride Solutions

A safe, simple, lightweight, and compact process generates high-purity hydrogen gas on demand from base-stabilized, aqueous solutions of sodium borohydride, NaBH4, by using a ruthenium catalyst. NaBH4 solutions can generate the equivalent of >2,500 Wh/L and >7% H2 by weight can be recovered. These inherently stable solutions do not generate significant amounts of H2 gas under ambient conditions. However, when in contact with heterogeneous Ru catalyst, NaBH4 solutions rapidly hydrolyze to form H2 gas and sodium borate, a water-soluble, inert salt. H2 generation only occurs when NaBH4 solutions are in contact with Ru catalyst. When Ru catalyst is removed from NaBH4 solution (or NaBH4 solution is separated from Ru catalyst), H2 generation stops. This H2 generator promises to be safer, have quicker response to H2 demand, have a greater H2 storage efficiency, and be more easily controllable than current H2 storage devices/generators. It can be easily incorporated into any system where H2 gas is required, such as powering internal combustion engines or fuel cells.